METHODS:
Patients with RA who experienced an inadequate response to MTX received MTX plus TCZ 162 mg subcutaneously. At 24 weeks, patients who achieved a Disease Activity Score in 28 joints using the erythrocyte sedimentation rate (DAS28-ESR) of ≤3.2 were randomized to receive TCZ monotherapy or to continue treatment with TCZ plus MTX until week 52. The primary outcome measure was the comparison of the mean change in the DAS28-ESR from week 24 to week 40 between the TCZ monotherapy and TCZ plus MTX arms (noninferiority margin of 0.6). Secondary outcome measures included worsening of the DAS28-ESR by ≥1.2, achievement of a DAS28-ESR of <2.6 and ≤3.2, and safety and immunogenicity.

RESULTS:
Among the 718 patients enrolled, 296 were randomized at week 24 to receive TCZ monotherapy (n = 147) or TCZ plus MTX (n = 147). The mean changes in the DAS28-ESR from week 24 to week 40 were 0.46 and 0.14 in the TCZ monotherapy arm and the TCZ plus MTX arm, respectively (weighted difference between the groups, 0.318 [95% confidence interval 0.045, 0.592]); discontinuing MTX in TCZ responders was noninferior to continuing MTX. Safety events were broadly similar between the randomized treatment groups; the most common serious adverse event was infection, which occurred in 2.1% of patients in the TCZ monotherapy group and 2.2% of patients receiving TCZ plus MTX.